A variety of radio paging devices and protocols are presently utilized in commercial paging networks. None of the known networks combines in one protocol individually addressable time slots intended for periodically active paging receivers, together with individually addressable time slots intended for continuously active receivers which receive long data messages.
U.S. Pat. No. 4,713,808 describes a high capacity time slot radio paging protocol (the "Gaskill protocol") comprising packets of information, each of which includes a receiver identification code and a message code. The packets are transmitted using subcarriers of conventional FM broadcast signals and are received using wrist mounted receiving devices.
U.S. Pat. No. 4,897,813 describes a paging system in which a series of time slots identify succeeding time slots that contain information for particular receivers.
The size and power requirements of the circuitry required to implement personal computers have decreased to such an extent that lap top portable personal computers are now in widespread use. Such lap top computers generally include all the normal personal computer functions and they generally include an LCD display.